What do the SPF Numbers on Sunscreen mean? What is the SPF number on the sunscreens? The higher the number, the better, right? Before you head out in the sun this summer, you should know a few things about SPF. What is it, exactly? What do the numbers mean, and how high can they go? We use sunscreen to block ultraviolet light from damaging the skin. There are two categories of UV light. The UVA- has more long-term damaging effects on the skin, like premature aging. UVB –causes sunburns.
SPF or sun protection factor, numbers were introduced in 1962 to measure a sunscreen’s effect against UVB rays. To determine a sunscreen’s SPF, testers round up 20 sun-sensitive people and measure the number of UV rays it takes them to burn without sunscreen. Then they redo the test with sunscreen. The “with sunscreen” number is divided by the “without sunscreen” number, and the result is rounded down to the nearest five. This is the SPF. SPF numbers start at 2 and have just recently reached 70.
To figure out how long you can stay in the sun with a given SPF, use this equation: Minutes to burn without sunscreen x SPF number = maximum sun exposure time For example, if you burn after 10 minutes of sun exposure, an SPF of 15 will allow you to be in the sun for up to 150 minutes without burning. You should know that this equation is not always accurate. People usually use far less sunscreen than the amount used in testing. In the real world, the average sun worshipper uses half the amount of sunscreen used in the laboratory, which could result in sunburn in half the time. My mom and her family grew up around a swimming pool.
They spend all day at the pool when we go out of town. My grandparents have to get cancer removed every year. It is true, a higher SPF number means more sun-exposure time. It also indicates the level of UVB absorption, but this number doesn’t increase exponentially, which can be confusing. For example, an SPF of 15 absorbs 93. 3 percent of UVB rays, but an SPF of 30 absorbs 96. 7 percent. The SPF number has doubled, but the absorption rate has increased by only 3. 4 percent. Because of the confusion about UVB absorption, the FDA proposed a cap on SPF numbers. Any sunscreen higher than 30 SPF would be a “30-plus. Thirty was the decided cap because above that, the percentage of UVB absorbed and overall protection of the skin increases only slightly, but people may misinterpret these higher SPF numbers as a much higher level of protection or even a guarantee of all-day protection. SPF| % UV absorbed | 2| 50 | 4 | 70 | 8 | 87. 5 | 15 | 93. 3 | 30 | 96. 7 | 50 | 98 | As helpful as the FDA was trying to be, the cap is clearly not in practice: Neutrogena and Hawaiian Tropic recently released sunscreens boasting an SPF of 70. We have sunscreens ranging from 15 SPF to 70 SPF in our cupboard at home.
There are several factors that allow all of us to get a sunburn even if we have sunscreen on. First, we don’t use enough. Second, despite waterproof or sweatproof labels, all sunscreens decrease in effectiveness when exposed to water or sweat. If you don’t apply the correct amount and then reapply after exposure to water, a 12-hour bake in the sun could give you a serious sunburn. The bottom line is that a sunscreen with a higher SPF does offer higher protection against UVB rays, but once you get past SPF 30, protection doesn’t increase very much, and the higher number may give you a false sense of protection.
Instead of letting SPF be your only guide to sun protection, avoid a burn by following a few simple sunscreen rules. 1. Know yourself: If you are whiter than a sheet of paper, if your Aunt Linda has skin cancer, or if you are sensitive to the sun because of a medication or a medical condition, take extra measures. Stay out of the sun as much as possible, wear a hat when you are out, use a broad-spectrum sunscreen with a high SPF and reapply that sunscreen often. Don’t put a lot of sunscreens on and layout by the pool. 2.
Look for “Broad-spectrum” label: The SPF number indicates protection only against UVB rays — many sunscreens, even those with a high SPF, allow UVA rays to be absorbed by the skin. UVA protection is usually indicated by a “broad-spectrum” label. Look for this label to ensure the most well-rounded sun coverage. Broad-spectrum sunscreen ensures protection from both UVA and UVB rays. The latest sunscreens boast new chemicals, like Mexoryl, which has proven to be one of the most effective UVA-blockers out there. 3. Be prepared- be proactive in planning: To be effective, sunscreen needs to be fully absorbed into the skin, so apply it 15 to 30 minutes before you even step into the sun. Make sure your whole family has taken the time to put sunscreen on. Then get ready for your time outdoors. 4. Reapply yourself: Whether you’re lying by the pool or mowing the lawn, you’ll probably be exposed to sweat or water, the natural enemies of sunscreen. To be safe, reapply after you swim or sweat. If you are going to a friend’s home or to the park, take a bottle with you. My mom keeps a bottle in each of our golf bags.
It takes almost 3 hours to play 9 holes in the junior league and it is extremely hot. 5. Full exposure: No matter how high the SPF, sunscreen can protect only the skin it covers. The most commonly missed spots are the temples, ears, back of the neck, and top of the feet. If you are sometimes guilty of losing your focus while applying your lotion, try one of the sunscreens that contain disappearing colorants, so you can identify unlotioned areas before they burn to a crisp. Our generation needs to learn from our parents and grandparents.
My grandma and grandpa Cox are always having skin cancer frozen or burned. My grandma has had a small part of her nose removed from malignant skin cancer. My mom grew up with a pool in her backyard her whole life. She spent so many years laying out in the sun with no sunscreen on. She also spent a year at BYU Hawaii so she could be in the sun. Our family is good about putting sunscreen on but we can all be better. I have learned so much about protecting my skin. This summer I am going to make a goal to wear sunscreen at the beginning of the day and have a bottle with me.
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